This invention relates to air cooling systems of spaces (domiciles, offices, stores etc.) whose desirable temperature is around 24xc2x0 C. The evaporative air cooling system consists of large moist surfaces which are created by a small mass of water within limited spaces and which can make use of the cooling effect caused by the vaporization of water into the free atmosphere, i.e. the ability of water to absorb heat during its vaporization. For the creation of these wet surfaces, the molecular powers of water (the powers of cohesion and relevance) as well as of other material with molecular powers relevant to those of the water, such as cotton, glass, metals etc are activated.
Evaporative coolers have been in use for many years as a cheap means of cooling. Such systems make use of the ability of water to absorb heat during its vaporization. Evaporative coolers are divided into two main categories: i) systems of direct cooling, ii) systems of indirect cooling. The systems of the first category, that is, the systems of direct cooling, exploit the cooling effect of water vaporization that takes place into the space to be cooled. Those systems suffer a major defect, since they cause the humidity of the air to increase and reach the point of saturation, a fact that makes those spaces unsuitable for habitation. Moreover, as the humidity increases, their performance decreases rapidly.
The technique of most of the indirect cooling systems is based on the cooling of an airstream by adiabatic saturation, which, in turn, is used to cool an airstream of the cooled space by heat conduction, which takes place into air-channels through which the cool air and the air of the space to be cooled circulate without mixing together. This method does not cause an increase of the absolute moisture of the space, however, it has a low performance. Many indirect evaporative coolers, in an attempt to improve their performance, use various systems of pre-cooling and dehumidification of the air that is cooled by adiabatic saturation, something which leads to costly and bulky arrangements and therefore not suitable for wider use.
The water feed device described in European Patent Application EP 0713060 A1 is a system of controlled feeding with water of a humidifier which is part of a special air-conditioning arrangement. However, it can use only pure or ultra pure water and it cannot create large moist surfaces within a limited space. Therefore, it is unsuitable for wider use in evaporative coolers for the cooling of habitable spaces.
The evaporative air-cooling systems of the present invention have the ability to create very large moist surfaces in a controllable way from which we exploit the cooling effect of the vaporization into the free atmosphere. Thus, the performance of these systems is almost constant without increasing the absolute moisture of the cooled space. In regions where the climate is hot and dry, the systems can replace in a cheap and friendly to the environment way, the heat pumps (air-conditioners) which have the following disadvantages:
i) They have a high buying cost and therefore they are inaccessible to large groups of the population. ii) Their function is very energy-consuming and, therefore, costly and detrimental to the environment. Moreover, the simultaneous use of a large number of them requires a huge power network that many countries cannot have. iii) The need for a regular maintenance by a trained staff which is quite expensive. iv) The danger of accidents. v) Their performance according to the Japanese standards JIS is measured under a temperature of 35xc2x0 C. outdoors and 27xc2x0 C. indoors. When the temperature of the environment exceeds 35xc2x0 C. they present a major failure in their performance whereas for temperatures over 44xc2x0 C., no guarantee of safe function is provided. vi) They cause a thermal pollution of the surroundings because they work as simple pumps of heat. They also pollute the atmosphere by dispersing the freon they use. vii) They do not renew the air of the space they cool. viii) In dry climates, such as the one in Greece, see Tables I and III, they dry the space that they cool even though this space is usually already in need of hydration.
The invention aims to create and maintain large wet surfaces with only a small mass of water and within a limited space, for the creation of which the molecular powers of water and of other material which present relevant molecular powers, e.g. cotton, metals, glass etc. are left to act. The invention makes use of the cooling effect caused by the vaporization of water on these surfaces into the free atmosphere. It contains a water source consisted of a pair of containers (A1) and (B1), linked together by a flexible pipe (C1) which allows the free movement of the container (B1). On the pipe there is a switch (E1). The pair of the containers is set on such a level so as to allow another pipe (F1) to feed other groovy-shaped containers with water from the container (B1) as communicating vessels. These new containers (G1) moisten cloths made of cotton which are in contact with and in fact cover the entire outside surface of containers of a (G2) type with small volume and large surface, whose side walls are made of a thin substance of a high thermal conductivity (e.g. copper, aluminium). These containers which are covered by the wet cloths are connected with insulated air-channels (S1) and (S2) through which and with the help of an electrical circulator (T1) (fan), the air of the air-conditioned (air-cooled) space circulates. In this way when a vaporization is effected through the wet cloths which cover the surface of the containers, the heat which is absorbed in priority is the one of the containers and of the air which moves inside them, causing inside the container a xe2x80x9cvaporizing coldxe2x80x9d. Therefore, when the air circulates inside the containers, it touches the walls producing heat and returns through the air-channel (S2) into the cooled room at a lower temperature. The heat that has been left onto the walls of the container is conducted to the small mass of water which lies on the surface of the containers and raises its temperature and its vaporization speed.
The evaporative air-cooling system in one of its realizations uses the openings of the rooms to be cooled, which are made of glass, e.g. doors or windows or of other non-perishable by water material, and places wet cloths on them, so that in the event of a vaporization from these surfaces into the free atmosphere, the heat needed in such a vaporization will be absorbed by the glass of these openings and as a result by the air inside the room, turning these partitions made of glass from principal gates of heat entry to gates of heat exit.
The system may also include an electrical fan which will be creating air streams onto the wet surface in order to accelerate the vaporization.
It may also include a system of collection and recycling of water which is not vaporized and through a pipe is sent into a container whereby it returns to the feeding container by means of a pump.
It may as well include a thermostat inside the room it cools, which will be activating the circulator and the fan. Furthermore, the system may include an air filter and a frame of variable extent with which the air will be cleaned and it will be renewed up to the desirable degree.
Finally, the system may include an outdoor thermostat which, by means of an electrical mechanism and according to the temperature of the environment, will serve to adjust the level of the container (B1) which in turn affects the quantity of water used to moisten the cotton cloths, so that the needs of the vaporization can be served.